<script src="http://code.jquery.com/jquery-1.8.2.js"></script>
<script src="jquery-ui.js"></script>

<script type="text/javascript" src="calendario.js"></script>
<link type="text/css" rel="Stylesheet" href="jquery-ui.css" />
<form action="/" method="post">
<label for="calendario">Data</label>
<input id="calendario" type="text" name="calendario" />
</form>

<input type="button" value="teste" onClick="teste()">

<script language="javaScript">

function teste(){
document.getElementById('ui-datepicker-div').style.display = 'block';
alert(document.getElementById('ui-datepicker-div').style.display);


}


</script>